Had the same problem . . .
My first week on 1-AD I did a 5X5 deadlift workout (I think) with close to 400 lbs. My form is pretty poor (due to a hip flexor flexibility problem), and the day after the workout, my lower back was OK. Five days later, I was getting chronic backpain from simply bending over! It hurt so bad I stopped deadlifting alltogether. It was so sore!
I've heard a lot of people on the juice say that it gives them flu like symptoms, including elevated body temp (very mild fever), red-flushed flesh, and incredibly back pain. I don't know what to say . . . after a week of leaving my lower back completely alone, the pain subsided. Now it is completely gone, five days after the end of my cycle. During the cycle, I did some PNF partner assisted back stretches (sit and reach with legs spread and someone pushing on my back), which helped tremendously, alongside frequent hot baths/use of the spa. I think that those two recuperation techniques really helped alot (after stretching, my back felt immediately better). So good luck to ya . . . at least your hair didn't fall out! (like mine did, LOL)